The present invention relates to a microphone unit, a close-talking voice input device, an information processing system, and a method of manufacturing a microphone unit.
It is desirable to pick up only desired sound (user's voice) during a telephone call, speech recognition, voice recording, or the like. However, sound (e.g., background noise) other than desired sound may also be present in an environment in which a voice input device is used. Therefore, a voice input device has been developed which has a function of removing noise so that the user's voice can be accurately extracted even when the voice input device is used in an environment in which noise is present.
As technology which removes noise in an environment in which noise is present, a method which provides a microphone unit with sharp directivity, and a method which detects the travel direction of sound waves utilizing the difference in time when sound waves reach a microphone unit and removes noise by signal processing have been known.
In recent years, electronic instruments have been increasingly scaled down. Therefore, technology which reduces the size of a voice input device has become important (see JP-A-7-312638, JP-A-9-331377, and JP-A-2001-186241).
In order to provide a microphone unit with sharp directivity, it is necessary to arrange a number of diaphragms. This makes it difficult to reduce the size of a voice input device.
In order to detect the travel direction of sound waves utilizing the difference in time when sound waves reach a microphone unit, a plurality of diaphragms must be provided at intervals equal to a fraction of several wavelengths of an audible sound wave. This also makes it difficult to reduce the size of a voice input device.